1. Field of the Invention
The invention concerns a transducer device for attachment to one end of a shaft of an electric drive. A “transducer device” describes a transducer or an assembly consisting of a support or carrier part and a transducer.
2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 1.98
It is known, for example, to glue magnetic transducer elements directly onto shaft ends or grooves in the shaft ends. This mounting option includes the risk of unwanted loosening of the adhesive bond, especially in the case of pump motors, e.g., oil pump motors filled with aggressive agents. In this case, associated sensor devices are usually separated from the sensor magnet through a sealed wall. Thus, wall thickness and clearance between a sensor magnet and a partition add up, thereby significantly limiting signal strength. In addition, routing field lines through the directly adjacent shaft weakens the field. It is therefore necessary to move the sensor transducer away from the shaft and bring it as close as possible to the partition without enlarging the structural space.
From U.S. Pat. No. 7,847,446 a generic transducer device is known, which is designed in the form of a magnet assembly. For securing the magnet assembly on the shaft, a magnet holder manufactured through injection molding and a magnetic element are used. The magnet holder and the magnetic elements are initially designed as separate components. In the assembled state, the magnetic element is injected into the plastic material of the magnet holder and the magnet holder connected to the shaft. Attachment is realized through a resilient tolerance ring, which is disposed in an insertion groove of the magnet holder. The magnet assembly increases the diameter of the shaft, thereby requiring more space. The additional spring element increases the number of parts required and complicates assembly. There is only a frictional connection between the shaft and the magnet assembly.
The problem addressed by the invention is therefore that of providing a generic transducer device which is particularly simple in design, reduces the number of parts and permits a particularly easy and secure assembly, thereby facilitating a captive and rotationally fixed connection.